New York State Building / Queens Museum of Art

The New York State Building is the sole surviving structure from
the 1939 World's Fair and is largely intact except for some
tawdry exterior "updates" that were probably added for
the 1964 fair. It briefly served as the home of the
United Nations prior to the construction of the UN facility
in Manhattan. It currently is incongruently home to a skating
rink and the Queens Museum of Art.
The QMA is perhaps most notable as the home of the
Panorama of the City of New York, a scale model of every
building in NYC that was built for the 1964 fair and
last updated in 1992.